A rotary member such as a drive shaft, a gear and so on used to transmit a torque from a prime mover to a desired portion or a member is vibrated inevitably by a pulsation of the torque or load, or by a friction. A frequency of the vibration is varied according to rotational speed, and high order vibrations such as secondary vibrations are also generated. Therefore, amplitude of vibrations is widened by resonance. As a result, noise is generated and durability of the rotary member is degraded. An example of a device or mechanism for suppressing such vibrations of equipment for transmitting power by rotation is disclosed in Japanese Patent Laid-Open No. 2011-504987.
Japanese Patent Laid-Open No. 2011-504987 describes a force transmission device which can suppress a pulsation of a torque from the prime mover. The transmission device described therein is comprised of: a lockup clutch which is arranged on a torque converter or a transmission route of a power from a turbine runner of the torque converter; an elastic damper that reduces vibrations by an elastic action of a spring; and a pendulum damper arranged on a rotary member of an output side of the elastic damper. In the force transmission device taught by Japanese Patent Laid-Open No. 2011-504987, the elastic damper and the pendulum damper are arranged in the torque converter and immersed in oil delivered thereto.
Thus, according to the teachings of Japanese Patent Laid-Open No. 2011-504987, those dampers are arranged inside of the torque converter to downsize the force transmission device. However, the torque converter is filled with the oil and a rolling member of the pendulum damper is immersed in the oil. Therefore, number of oscillation of the pendulum damper may be changed by a viscosity resistance of the oil and vibration damping effect may be reduced.